Sorry if this sounds contrary or condescending, it's not meant to be.
Those plugs in the block & head are NOT "freeze plugs... meant to pop out and save the block from cracking." They are casting holes, there to hold the internal sand casting in place relative to the outside of the block/head, which creates the internal passages inside the block & heads. While they may (or may not) pop out if the coolant freezes inside the block/head, that is not what they are there for. Even if they DO pop out if the coolant freezes, this will by no means mean the block/head is NOT cracked.
Sorry to be a "nit-picker" but although these plugs are commonly called "freeze plugs" & most everyone knows them as such, that is NOT why they are there. They are "casting plugs."